Tropical Storm Isaac predicted to erode beaches and dunes

Tropical Storm Isaac is likely to cause erosion of beaches and dunes over 89 percent of the Mississippi coast and 45 percent of Alabama's coast, according to a statement released by the National Hurricane Center this morning (Aug. 27).

Seventy-eight percent of Florida's central west coast and 23 percent of the Panhandle are also very likely to face erosion from Tropical Storm Isaac's storm surge and pounding waves, according to a statement released by the U.S. Geological Survey on Friday (Aug. 24).

This is bad news for the many Florida beaches that were eroded by Topical Storm Debby in June.

"With Isaac bearing down on Florida beaches so soon on the heels of Debby, this is like a 'one-two punch' for the dunes that provide coastal protection," USGS Director Marcia McNutt said in the statement.

Using a USGS-developed model, scientists incorporated measurements of beach elevation and wave and surge forecasts to determine the probabilities of collision, overwash and inundation during the coming storm.

Collision is when waves attack the base of dunes and cause erosion there. Overwash is when waves and water from storm surges rush over dunes and carry sand further inland. Twenty percent of Mississippi's coast and 8 percent of Alabama's coast are likely to experience overwash, according to the NHC.

Inundation, the most extreme of the three, occurs when increased water levels completely submerge beaches and dunes. This isn't expected to happen with Isaac.

The team will revise its calculations as storm track and intensity forecasts are updated, and will change their projections on their website.